Distinct profile and prognostic impact of body composition changes in idiopathic pulmonary fibrosis and idiopathic pleuroparenchymal fibroelastosis

Change in body composition with skeletal muscle wasting, a major component of pulmonary cachexia, is associated with mortality in chronic obstructive pulmonary disease and cancer. However, its relevance in interstitial lung diseases (ILDs) remains unclear. We hypothesized changes in body composition would be associated with mortality in ILDs. We measured the cross-sectional-area (ESM(CSA)) and muscle attenuation (ESM(MA)) of erector-spinae muscles, as determined by CT-imaging, in patients with idiopathic pulmonary fibrosis (IPF; n = 131) and idiopathic pleuroparenchymal fibroelastosis (iPPFE; n = 43) and controls. Subsequently, implications with prognosis were evaluated. The ESM(CSA) of ILD patients, but not ESM(MA), was significantly smaller than that in controls. Lower ESM(CSA) with decreased BMI were recorded in iPPFE patients versus IPF patients, whilst IPF patients had decreased ESM(CSA) without BMI decline. Lower ESM(CSA) in IPF patients were associated with poorer prognoses. Conversely, decreased ESM(MA) were associated with worse survival in iPPFE patients. Multivariate analyses showed that ESM(CSA) in IPF and ESM(MA) in iPPFE were independent risk factors for mortality. Distinct changes in body composition had prognostic significance among patients with IPF and iPPFE. Lower ESM(CSA) and ESM(MA) were independently associated with poor prognosis in IPF and iPPFE, respectively. These results suggest values to measure body composition changes in managing patients with IPF and iPPFE.